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How Did They Tell Time Before Clocks?

Lets Examine How Did They Tell Time Before Clocks? Where Did Telling Time Originate?What makes time so important?Who invented the clockand why worldwide exist many various time zones?
The very first kind of telling time was the sundial and the earliest sundials are known from the archaeological record are obelisks from almost 5,000 years earlier. Sundials suggest the time by casting a shadow onto a surface. The things that cast the shadow is a stick in the center known as a gnomon. A sound sundial can determine time with exceptional precision, and sundials were used to monitor the efficiency of clocks until the modern period.

However, sundials have their limitations too. Undoubtedly they require the sun to shine, They do not work throughout the night when it's dark. 
Several devices have been utilized throughout the years to estimate the passage of time. candle lights and sticks of incense that burn down at fairly predictable speeds have been used, in addition to the hourglass.

Hou…
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Two T-38s traveling faster than the speed of sound (shock waves visible)

To get the image, NASA utilized a Super King Air turboprop airplane flying at an indicated airspeed of about 160 miles per hour at 30,000 feet. 

The two supersonic jets, separated by about 30 feet front to back and 10 feet vertically, were listed below the King Air by about 2,000 feet when it shot the images. 
The shock waves were photographable because of the modification in air density. "The density modification triggers a modification in the index of refraction," Banks states. A spoon will look distorted when you see it immersed in a glass of water. 
It turns out that images of shockwaves triggered by flying faster than the speed of sound are amazing to see, even without the sound. 

NASA photographed 2 T-38 airplanes flying at merely faster than the speed of sound over California. The King Air has ports on its stomach that can be opened or closed, and the photography equipment was placed in among those ports so it might shoot downwards. 
The turboprop doing the shooting was st…

Moon’s gamma-ray glow from NASA’s Fermi Gamma-ray Space Telescope

Steadily improving view of the Moon’s gamma-ray glow from NASA’s Fermi Gamma-ray Space Telescope. Each 5-by-5-degree image is centered on the Moon and shows gamma rays with energies above 31 million electron volts, or tens of millions of times that of visible light. 
At these energies, the Moon is actually brighter than the Sun. Brighter colors indicate greater numbers of gamma rays. This image sequence shows how longer exposure, ranging from two to 128 months (10.7 years), improved the view.
If our eyes could see high-energy radiation called gamma rays, the Moon would appear brighter than the Sun! That’s how NASA’s Fermi Gamma-ray Space Telescope has seen our neighbor in space for the past decade.

Gamma-ray observations are not sensitive enough to clearly see the shape of the Moon’s disk or any surface features. Instead, Fermi’s Large Area Telescope (LAT) detects a prominent glow centered on the Moon’s position in the sky.

Scientists have been analyzing the Moon’s gamma-ray glow as a way…

NASA researching how climate change is adding to more regular forest fires

On July 7th, 2019 the skies around Anchorage Alaska were thick with smoke. Across the Cook Inlet, the Swan Lake Fire had spread over nearly 79,000 acres and was still growing. This was just one of over 400 fires that burned in Alaska so far in 2019.

Climate change and forest fires In the Arctic, fires can help rejuvenate ecosystems and make way for new growth. However, Arctic and boreal regions are warming at a faster rate than anywhere else on Earth, and hotter and drier summers are leading to accelerated fire cycles and more intense burns.

Elizabeth Hoy: Fires in boreal forests are different than in other areas of the world, such as those in the western United States. One of the main differences is they have these really thick organic soils layers and these soil layers burn.

And so you’re not just getting fires in the trees or in the canopy, you’re getting fires below the tree itself, like in that soil layer and that is really when you get a lot of these carbon emissions.

Researchi…

Researchers developed a way to deal with cancerous tumors that are resistant to immunotherapy

Researchers from the US and Israel found a way to deal with tumors that developed a resistance to immunotherapy
In recent years, the field of cancer treatment with immunotherapy has made headlines. Medications of this type activate the immune system and mobilize it against the cancerous growth, thus helping the body to destroy the malignant cells on its own. But many cancerous tumors manage not only to passively evade the immune system, but also to display proteins on their cell membrane that "cheat" the immune system and make it think the cell is normal.

In order to deal with them, a specific type of immunotherapy called checkpoint inhibitors has been developed, which prevents communication between the tumor and the immune system, thus preventing it from delaying its activity. These medications are not directed directly at the tumor, but rather prevent it from evading the immune system. Their use requires initial mobilization of the immune system in the cancerous environment,…

A new automated system that is capable of producing organs from stem cells

Organoids: mini organs in a petri dish for disease research and new curesA new automated system developed at the University of Washington is capable of efficiently producing mini organs from stem cells, and thereby has the potential to accelerate biomedical science and research.

Normally, when a researcher wants to test medications or treatments on cells from a particular tissue - for example, a liver - he should first grow the cells in the laboratory in a petri dish. The cells grow on the bottom of the dish and form a thin two-dimensional tissue that does not reflect what happens in the complex three-dimensional tissue that exists in the body. In recent years, researchers have been able to make stem cells develop into three-dimensional structures more like those in the body, called mini-organs. Researchers are able to test different treatments for the mini-organs, and to be more confident that they actually reflect what happens in the living body.

But there is one big problem: produci…

Findings from an archaeological site in Jordan indicate that dogs lived with humans 11,500 years ago

The transition from hunter-gatherer societies to farmers' societies
The people who lived 11,500 years ago in the area that is today northeast of Jordan apparently did not know this, but they were in the midst of one of the most important changes in human history: the transition from hunter-gatherer societies to farmers' societies. This is the change that led to the development of cities and then kingdoms, and ultimately to all human civilizations. These people already lived in permanent settlements, and began to use more and more plants and animals in their environment. And they had something else: dogs. 

In a new article, researchers from Denmark and the United Kingdom suggest that dog domestication have contributed to the expansion of resources available to people of the period, and that the dogs mainly helped to hunt relatively small prey, such as rabbits.
Those whose remains were found at a site known as Shubayqa 6 lived in basalt stone structures, with a stone floor, which …